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I noticed two statements by the author which could do with some expansion:

In addition, it would be beneficial for us to reside in the company of as many alien civilizations as possible with whom we could share technology, for the same reason that animals feel empowered by congregating in large herds.

My understanding is that herds are collections of herbivores and are one way which has evolved to help protect against predation. While our descendants might differ from us, I tend to suspect that our own grouping would more likely be considered to be in the latter category; i.e. as a predatory pack instead of an herbivorous herd. Our local cluster is quite small, so (taking the proposal at face value) our descendants would have to go elsewhere.

Some lucky civilizations were born in clusters and inherited the resources around them without the need to travel. Could others develop the technology that would enable them to reach the nearest galaxy cluster fast enough?

In other words, those already there are likely to object strenuously to newcomers trying to make use of their resources. But see my comment above.

The search for a strategy for mankind to survive the solar Red Giant catastrophe

M. Taube, W. Seifritz
(Submitted on 25 Nov 2008)

In around 5 gigayears our Sun will grow to a Red Giant and will swallow Earth. The plan is subdivided into two parts: We propose to construct some kind of parasol to shadow Earth. The position of the parasol will be the (inner) Lagrange Point L1. If we want to survive also the time beyond the next 5 Gy, where Suns luminosity and radius increase hundred fold and oscillate until our Sun develops finally into a White Dwarf, we have to shift Earth into the Kuiper Belt (50 AU) by means of the swing-by technique During this journey of about some megayears or more Earth must be illuminated by an artificial light source. A ring of DD-fusion power stations outstretched on Moons orbit should produce the necessary 175 PW of visible light. In the Kuiper Belt Earth will be brought into an orbit of an artificial Sun, an ArtSun formed in the meantime by the fusion of gaseous Jupiter-like planets imported from other planetary systems in the neighborhood .

There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.
— Mark Twain, Life on the Mississippi (1883)

During this journey of about some megayears or more Earth must be illuminated by an artificial light source. A ring of DD-fusion power stations outstretched on Moons orbit should produce the necessary 175 PW of visible light. In the Kuiper Belt Earth will be brought into an orbit of an artificial Sun, an ArtSun formed in the meantime by the fusion of gaseous Jupiter-like planets imported from other planetary systems in the neighborhood .

If we have mastered artificial lighting/heating, why would another Sun be needed?

"I'm planning to live forever. So far, that's working perfectly." Steven Wright

One possibility might be that the new sun could be used as a gravitational tug to transport its accompanying planets on a long journey to more accommodating environments, where more resources are available, perhaps. Therein lies some "hard" SF stories, perhaps. (Some such already have been written.)

On arrival the star could then be disassembled by starlifting. All these processes take billions of years. But a civilisation which colonises long-lived red dwarf systems will have a trillion years or more to play with.

The search for a strategy for mankind to survive the solar Red Giant catastrophe

M. Taube, W. Seifritz
(Submitted on 25 Nov 2008)

In around 5 gigayears our Sun will grow to a Red Giant and will swallow Earth.

Does anyone really think there will be humans, or humanoids, or anything resembling such animals in 5 gigayears?!
I dont expect any wise learned entity in even a 100m years caring at all for anything about our plans for their future.

We don't have 5 billion years. The Earth will become uninhabitable (to all but thermophiles) long before that.

Multicellular life will go extinct about 800 million years in the future apparently. Things will start to get difficult long before that.

Only 800 million years? We'd better hurry!

Seriously, though, if we're not living and thriving off Earth long before then it'll be because we wiped ourselves out. And if our distant descendants (or creations) have expanded into the Universe by then, they'll probably have the capacity to do something about saving life on Earth. Gravity-drag the planet away over a few million years with close asteroid passes. Planetary sunshades, probably with their own civilizations living on them. Starlifting to relieve or delay the Solar expansion. etc.

"I'm planning to live forever. So far, that's working perfectly." Steven Wright

Seriously, though, if we're not living and thriving off Earth long before then it'll be because we wiped ourselves out. And if our distant descendants (or creations) have expanded into the Universe by then, they'll probably have the capacity to do something about saving life on Earth. Gravity-drag the planet away over a few million years with close asteroid passes. Planetary sunshades, probably with their own civilizations living on them. Starlifting to relieve or delay the Solar expansion. etc.

I consider the Orion's Arm scenario conservative. And they would probably be able to do this in 12,569 AD.